全文获取类型
收费全文 | 89篇 |
免费 | 1篇 |
国内免费 | 19篇 |
专业分类
化学 | 102篇 |
晶体学 | 4篇 |
物理学 | 3篇 |
出版年
2023年 | 1篇 |
2021年 | 3篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 12篇 |
2012年 | 9篇 |
2011年 | 6篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 1篇 |
2004年 | 8篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有109条查询结果,搜索用时 203 毫秒
81.
Xiao‐Juan Xu 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(11):1029-1032
A metal coordination polymer, {[Mn2Mo(CN)8(C12H8N6)(CH3CN)2(H2O)2]·2H2O}n, has been synthesized by the reaction of Mn(ClO4)2·6H2O with 3,6‐bis(pyridin‐2‐yl)‐1,2,4,5‐tetrazine (bptz) and (Bu3N)3[Mo(CN)8] at room temperature. The polymer was characterized by IR spectroscopy, elemental analysis and X‐ray diffraction, and the magnetic properties were also investigated. The X‐ray diffraction analysis reveals that the compound is a new three‐dimensional coordination polymer with a PtS‐type network. Magnetic investigation shows antiferromagnetic coupling between adjacent Mn2+ cations. 相似文献
82.
83.
采用C++自编译程序及组合原理,设计并筛选出一种未见报道的新型富氮类高能量密度化合物-3,6-双(3,5.二硝基.1,2,4-三唑.1)-1,2,4,5-四嗪-1,4-二氧化物,用B3LYP法,在6-31G**基组水平上得到该化合物全优化构型;在振动分析的基础上求得体系的振动频率、IR谱;通过键级分析得到热解引发键的键离解能(BDE);采用Monte-Carlo 方法预估了密度;设计等键等电子反应计算了生成焓;运用Kamlet-Jacobs公式预测爆速、爆压和爆热;运用Keshavarz 等推导的预估撞击感度H50的公式预测了撞击感度性能;并利用逆合成分析法设计其合成路线.结果表明:该化合物存在8个强吸收峰,校正后的热解引发键的BDE为264KJ·mol-1,稳定性较优;密度1.955 g·cm-3、生成焓901.72 kJ·mol-1、爆速9191.48 m·s-1、爆压39.32 GPa、爆热6705.15 j·g-1;撞击感度H50为55.85cm,低于黑索金(RDX)和奥克托今(HMx);以上性能均达到了高能量密度化合物的标准,且该化合物设计合成路线步骤较少、原料易得,有望得到广泛应用. 相似文献
84.
Bozhou Wang Weipeng Lai Qian Liu Peng Lian Yongqiang Xue 《Frontiers of Chemistry in China》2009,4(1):69-74
3,6-bis(1H-1,2,3,4-tetrazol-5-yl-amino)- 1,2,4,5-tetrazine (BTATz) was synthesized by the condensation of triaminoguanidinium
nitrate with 2,4-pentanedione, followed by oxidation and substitution reaction. The product was characterized by elemental
analysis, IR, NMR spectrometry and DSC analysis. Instead of nitrogen dioxide/N-methylpyrrolidone, acetic acid/sodium nitrite
was used as the oxidizer during the oxidation. Thus, the cost was reduced and the process was simplified. The theoretical
properties of BTATz were estimated by a B3LYP method based on a 6-31G(d,p) basis set, and the stable geometric configuration
and bond order were obtained. The vibrational frequencies, IR spectrum and thermodynamic properties under different temperatures
were obtained from vibrational analysis and the relationship between temperature and thermodynamics properties was deduced.
Pyrolysis mechanism of BTATz was discussedand the transition state and activation energy of ring opening reaction of the tetrazole
were deduced.
__________
Translated from Chinese Journal of Organic Chemistry, 2008, 28(3) (in Chinese) 相似文献
85.
Lei Wang Jia-Xiang Yang Wen-Tao Yu Yan Ren Qian Xin Zhi Liu Min-Hua Jiang 《Journal of solid state chemistry》2004,177(11):4293-4299
A conjugated and symmetric multi-branched compound, 1,2,4,5-tetrakis(4-pyridylvinyl)benzene (TKPVB), has been synthesized and the crystal structures of TKPVB and its intermediate, 1,2,4,5-tetrakis(dimethoxyphosphorylmethyl)benzene, were determined by diffraction method. TKPVB with four units of 4-vinylpyridine moieties attached to the central benzene core presents an A-π-A general framework, where A is a π-deficient pyridine ring. The single-photon and two-photon absorption and fluorescence properties in different solvents of varying polarity have been investigated. It is also found that the one- and two-photon-induced fluorescence spectra are quite similar, which indicate that the one- and two-photon allowed-excited states are the same. 相似文献
86.
The reaction between freshly precipitated silver oxide Ag2O and an aqueous solution of tetrabenzenecarboxylic acid H4L leads to the anhydrous Ag2H2L complex. It crystallizes in the space groupP21/c, witha=6.457(1),b=8.180(1),c=9.982(1) Å, β=97.83(1)°,V=522.3(1) ?3,Z=2,d=2.976 g cm−3. This structure is a three dimensional polymeric network polymer without any silver...silver interaction. The silver environment
is a bipyramid trigonal polyhedron with three short bond distances in the equatorial plane (Ag−O=2.255(2), 2.295(2), and 2.499(2)
Å) and two longer bond distances in axial positions (Ag−O=2.558(2) and 2.617(2) Å). Thus, the silver polyhedron involves five
different ligands. It is noteworthy that the (H2L2)2− ligand is located around an inversion centre. 相似文献
87.
Silica-supported boron trifluoride (BF3·SiO2) is an efficient, readily available and reusable catalyst for the synthesis of 1,2,4,5-tetrasubstituted imidazoles using benzil, an aromatic aldehyde and an amine in the presence of ammonium acetate. This one-pot procedure is very simple, affording good to excellent yields. 相似文献
88.
Kinga Wzgarda-Raj Justyna Dominikowska Sławomir Wojtulewski Agnieszka J. Rybarczyk-Pirek 《Acta Crystallographica. Section C, Structural Chemistry》2023,79(2):52-60
The results of the X-ray structure analysis of three novel 3,6-bis(pyridin-2-yl)-1,2,4,5-tetrazine cocrystals are presented. These are 3,6-bis(pyridin-2-yl)-1,2,4,5-tetrazine–2,4,6-tribromophenol (1/2), C12H8N6·2C6H3Br3O, 3,6-bis(pyridin-2-yl)-1,2,4,5-tetrazine–isonicotinic acid N-oxide (1/2), C12H8N6·2C6H5NO3, and 3,6-bis(pyridin-2-yl)-1,2,4,5-tetrazine–4-nitrobenzenesulfonamide (1/1), C12H8N6·C6H6N2O4S. Special attention is paid to a conformational analysis of the title tetrazine molecule in known crystal structures. Quantum chemistry methods are used to compare the energetic parameters of the investigated conformations. A structural analysis of the hydrogen and halogen bonds with acceptor aromatic tetrazine and pyrazine rings is conducted in order to elucidate factors responsible for conformational stability. 相似文献
89.
选择刚性的1,2,4,5-均苯四甲酸(H4L)为主配体,以1,3-双(1H-咪唑-1-基甲基)苯(1,3-bib)为辅助配体,在水热条件下,与过渡金属离子Cd2+配位合成了配合物[Cd(L)0.5(1,3-bib)(H2O)]·H2O(1)。利用元素分析、红外光谱、X射线单晶衍射、热重和X射线粉末衍射对其结构进行了表征,并研究了化合物的荧光性质。结果表明:配合物1属正交晶系,空间群Pbca,a=0.85708(4)nm,b=1.91223(10)nm,c=2.45160(12)nm。配合物1中Cd2+与L4-配体的羧基通过双齿螯合配位,通过1,3-bib连接形成三维网状结构。配合物1具有较强的荧光,其对丙酮溶剂、MnO-4、Hg2+离子有一定的荧光猝灭。 相似文献
90.
Andrew J. McKerrow Marye Anne Fox Jihperng Leu Paul S. Ho 《Journal of polymer science. Part A, Polymer chemistry》1997,35(2):319-327
N,N′-Di-(4-anilino)-1,2,4,5-benzene bis(dicarboximide) was prepared in a three-step synthesis and purified by heating the resulting solid to 200°C. Condensation of the diamino-diimide with several dianhydrides (BPDA, BTDA, and 6-FDA) yielded polyamic acid-imides that could be either thermally or chemically cured to the corresponding alternating copolyimides. Imidization of the polyamic acid-imide to the final polyimide was monitored by FTIR for samples coated on silicon wafers before being thermally cured. Polyimides prepared by chemical imidization were found by thermogravimetric analysis to be stable to temperatures of 600°C. © 1997 John Wiley & Sons, Inc. 相似文献